In looking closer at your pictures it became obvious to me
that you do have to replace/repair at least the section by the door. All that I mentioned before still applies but you're going to have to deal with getting the new wood under the wall. There are lots of posts in the forums about how to do this so do some searching and you'll find it.
As for the rest of the floor you might consider sealing with something like marine grade (spar varnish) varnish to protect the wood surface from moisture.
Brad